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powerpc/xmon: Fallback to printk() in xmon_printf() if udbg is not setup 

It is possible to configure a kernel which has xmon enabled, but has no
udbg backend to provide IO. This can make xmon rather confusing, as it
produces no output, blocks for two seconds, and then returns.

As a last resort we can instead try to printk(), which may deadlock or
otherwise crash, but tries quite hard not to.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Michael Ellerman 2012-10-09 04:20:47 +00:00 committed by Benjamin Herrenschmidt
parent 0104cd6839
commit b2bb65f680
1 changed files with 8 additions and 2 deletions
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10
arch/powerpc/xmon/nonstdio.c
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@ -111,13 +111,19 @@ char *xmon_gets(char *str, int nb)
void xmon_printf(const char *format, ...)
{
va_list args;
int n;
static char xmon_outbuf[1024];
int rc, n;
va_start(args, format);
n = vsnprintf(xmon_outbuf, sizeof(xmon_outbuf), format, args);
va_end(args);
xmon_write(xmon_outbuf, n);
rc = xmon_write(xmon_outbuf, n);
if (n && rc == 0) {
/* No udbg hooks, fallback to printk() - dangerous */
printk(xmon_outbuf);
}
}
void xmon_puts(const char *str)